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IC 8855 



Bureau of Mines Information Circular/1981 




Uranium Mine Ventilation Costs 



By Robert C. Bates 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8855 



Uranium Mine Ventilation Costs 



By Robert C. Bates 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 




As the Nation's principal conservation agency, the Department of the Interior 
has responsibility for most of our nationally owned public lands and natural 
resources. This includes fostering the wisest use of our land and water re- 
sources, protecting our fish and wildlife, preserving the environmental and 
cultural values of our national parks and historical places, and providing for 
the enjoyment of life through outdoor recreation. The Department assesses 
our energy and mineral resources and works to assure that their development is 
in the best interests of all our people. The Department also has a major re- 
sponsibility for American Indian reservation communities and for people who 
live in Island Territories under U.S. administration. 



■ C/i/ 



This publication has been cataloged as follows: 



Bates, Robert C 

Uranium mine ventilation costs. 

(Information circular ; 8855) 

Bibliography: p. 18. 

Supt. of Docs, no.: I 28.27:8855. 

1. Uranium mines and mining— Safety measures. 2. Mine ventila* 
tion— Costs,, I. Title. II. Series: Information circular (United States. 
Bureau of Mines) ; 8855. 



TN295.U4 622s [338.2'3] 81-607862 AACR2 



For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 



CONTENTS 



Page 



Abs tract 1 

Introduction 1 

Background 2 

FRC staff report 2 

RMC report 4 

ADL study 7 

Analysis 9 

Applications 12 

Cost of other control measures 16 

Conclusions 17 

References 18 

ILLUSTRATIONS 

1 . Cost per ton for ventilating uranium mines 10 

2. Costs for ventilating uranium mines versus average annual exposure 

with regression line 12 

3. Projected radiation control cost for different Consumer Price 

Indices and average annual exposures 14 

4. Project radon-daughter control costs versus limiting miner exposure 

WLM for several Consumer Price Index values 15 

TABLES 

1. Ventilation cost estimates, 11-mine study, 1965 3 

2. Ventilation cost estimates, 3-mine study 3 

3. Modified WL-control cost for three smaller mines 5 

4. Radon-daughter control costs for five large uranium mines 6 

5. Costs and radiation levels for various degrees of control 8 

6. Federal Radiation Council Report 8 uranium mine ventilation cost 

data converted to 1967 dollars per ton 9 

7. Uranium mine ventilation cost data from Spencer converted to 

1967 dollars per ton 10 

8. Average ventilation costs and working place radon-daughter 

concentrations 11 

9. Consumer Price Index (1967 = 100) 13 

10. Cost per ton at CPI = 250 (1980$) for several average WLM exposures 13 

11. Cost per ton at CPI = 250 for several limiting miner exposures WLM. 15 

12. Cost for radon control, from Kown 16 



URANIUM MINE VENTILATION COSTS 
by 

Robert C. Bates 1 



ABSTRACT 

This Bureau of Mines report converts published data on the cost of venti- 
lating uranium mines to a common price base and analyzes these data to deter- 
mine the cost per ton of uranium ore at various levels of radiation exposure 
control. There appears to be an exponential increase of cost as the radiation 
level is lowered. The 1967 base costs are extrapolated to present dollars, 
and some cost comparisons are given for other radiation control measures. 

INTRODUCTION 

Since about 1950, the Bureau of Mines has been concerned about radon- 
daughter concentrations in uranium mines. For a considerable time, this 
interest was primarily oriented toward control by ventilation. Ventilation is 
the most common airborne-radiation control measure used in uranium mines. 
However, as the mines become deeper and larger, ventilation costs increase 
tremendously and all available radiation control methods must be used to help 
reduce the radiation hazards. 

In 1973, the Bureau began investigating other methods to control 
airborne-radiation levels and reduce ventilation requirements. Laboratory, 
field, and theoretical evaluations were made of sealants, bulkheading, radon 
removal, overpressurization, and radon-daughter removal. Costs were deter- 
mined for several control techniques. For example, the cost for removing 
radon from the air was found to be prohibitive (2), 2 

In 1973, a Bureau study was performed of data from three reports (1_, 6^, 
10 ) to estimate the cost of mine ventilation in terms that could be related 
to control measure costs. These were the only reports that had seriously 
discussed the cost of ventilating uranium mines. Since then, a study of 
procedures for setting standards for radon-daughters has become available (5). 
It evaluated the information in the three previous reports and, among other 

Supervisory mining engineer, Spokane Research Center, Bureau of Mines, 

Spokane, Wash. 
2 Underlned numbers in parentheses refer to items in the list of references at 

the end of this report. 



things, developed an exponential equation for ventilation costs. The informa- 
tion given in the literature is not directly applicable for cost comparisons. 
Therefore, the following text describes these three studies, describes the 
analysis methods, compares the results with those of Cross (5) , projects the 
costs for various radon-daughter exposure limits, and comments on some costs 
of radon and radon-daughter control measures. 

BACKGROUND 

The three reports studied ^1_, 6_, 10 ) had been sponsored by the Federal 
Radiation Council. The analysis base and philosophy for each were somewhat 
different, thus making direct comparisons difficult. For example, three dif- 
ferent parameters were used as the exposure bases for the three reports — aver- 
age working level, 3 mine index, and "last man" working level. The mine 
average WL might or might not be representative of the miners' exposure, 
because extremely low values in haulageways or intake shafts can be averaged 
with the supposedly higher ones in the stopes. A more representative value 
for the person's exposure is the mine index, which uses the weighting of occu- 
pancy time and the number of persons involved to calculate the average. The 
third concept, the "last man" working level exposure, represents the highest 
annual exposure recorded„for any underground personnel. The ventilation costs 
are also given in two different ways, dollars per ton of ore produced and 
dollars per pound of U3O8. The information available in these reports is 
described briefly in the following paragraphs. 

FRC Staff Report 

A Federal Council (FRC) staff report (6) summarizes quite a bit of the 
information available on the radiation problem in uranium mines. Although 
various control methods were available, ventilation was the most important. 
Since published information on ventilation costs was not available, the FRC 
staff requested a number of uranium mining companies to carry out ventilation 
cost studies. As they state (6_, p. 34), "These estimates are intended to 
illustrate the general magnitude of cost in a few selected mines and are not 
applicable to the industry as a whole." The studies were divided into two 
groups. One covered 11 larger underground mines that accounted for more 
than 20 pet of the U.S. uranium ore production, and the other group covered 
3 mines that produced about 2 pet of the national total. 

An exposure index was developed for the first group using time-weighted 
average exposures that were weighted by the number of persons involved in each 
of the worker categories. Estimates were made of the radon-daughter concen- 
trations for minimal ventilation, and costs were tabulated for various levels 
of radiation control. Ventilation and operating costs were projected over a 
10-year period. Table 1 in their report is repeated here as table 1. 



3 "Working level" (WL) means any combination of the short-lived radon daughters 
in 1 liter of air that will result in the ultimate emission of 1.3 x 10 5 
million electron volts (MeV) of alpha energy. 



TABLE 1. - Ventilation cost estimates, 11-mine study, 1965 (_6) 

(Million dollars) 





Investment 


Operating cost 


Total cost 


Estimated mine 




cost 


(10-year est.) 


( 1 0-year s) 


index WL 


Past experience 


3.9 


7.9 


11.8 


l 2 


Estimated ventilation 










cost without radon 












2.0 


2.8 


4.8 


2 10 


Additional cost for 




radon control from 












1.9 


5.1 


7.0 




Estimated additional 










cost to reduce from 












1.5 


6.0 


7.5 


1 


Total cost to control 










at 1 WL — 10 years.. 






19.3 





Composite mine index for 1965. 
2 Estimate of what the average WL concentration would be with normal 
ventilation practices. 

The second group of three mines was considerably different from the 
11 mines in geology, depth, extent of working, productive capacity, arrange- 
ment of passageways, numbers of openings, and so on. The reporting of the 
information was also different. Ventilation and operating costs were pro- 
jected over a 6-year period instead of a 10-year period, and the working-level 
values were reported as 1-year averages, rather than the mine index value used 
for the 11-mine study. Table 2 of the FRC staff report (6) is given in its 
entirety as table 2 in this report. 

TABLE 2. - Ventilation cost estimates, 3-mine study (_6) 

(Thousand dollars) 





Investment 
cost 


Oper. cost 
(6-year est. ) 


Total cost 
(6-years) 


Average 
concentration, 
WL 


Past experience: 


361 

321 

75 


120 
85 
50 


481 
406 
125 


x 1.4 


Mine B 


H.5 




H.5 




757 

63 

66 

6 


255 

21 

18 

4 


1,012 

84 
84 
10 




Estimated for case of 
minimum ventilation: 




Mine B 


2 5-20 








135 


43 


178 





1 Average WL concentrations in 1965. 
2 Estimate of what the average WL concentrations would be with normal 
ventilation practices. 



RMC Report 

Spencer (10) of the Resource Management Corp. (RMC) examined a number of 
items, including costs, associated with the control of radon daughters in ura- 
nium mines. Although literature was collected, much of the information came 
from personal discussions with knowledgeable government and industry people. 
From these discussions, Spencer decided to limit their studies to the Colorado 
Plateau region (Uravan mineral belt and Ambrosia Lake). Their evaluations 
also led RMC to the conclusion that only two approaches, historical and mod- 
eling, appeared usable for cost estimating. Historical data could provide a 
relationship between cost and working levels from which they could extrapolate 
to the average mine with a 0.3-WL concentration. Although this technique has 
a number of inadequacies stemming from the wide range in the characteristics 
of the mining operations supplying the data, it was possible for RMC to 
arrive at some figures in a very short time. The modeling approach, because 
of the complexity of the mining process itself, was too complex for the short 
time period of the study. Therefore, data were requested and received from 
eight operating mines (three small and five large) for 3 years of production, 
1966, 1967, and 1968. 

The three small mines had relatively small output tonnages but fairly 
large underground areas* Costs included supplies, labor, power, air courses, 
and capital investments. Capital and ventilation costs for drifts and raises 
were amortized over a 5-year period. The capital expenditures were reportedly 
amortized over a 10-year period. A summary of their data is given in table 3. 
The radon-daughter concentrations are given as average working levels. 



TABLE 3. - Modified WL-control cost for three smaller mines (10) 



Mine and year 


Ore output, 
10 3 tons 


Average con- 
centration, WL 


Cost per ton 
of ore 1 


Modified cost 

per ton of 

ore 2 


Mine A: 3 

1966 


12 
9.4 
7.7 

H.O 
3.0 
2.2 

34.1 
36.2 
29.3 

16.7 
16.2 
13.1 


2.2 
2.1 

.7 

3.1 

2.1 

.6 

1.3 
1.3 

.5 

1.66 

1.50 

.55 


$0.33 

1.10 

.51 

.47 

1.38 

.90 

.21 

.47 

2.19 

.26 

.65 

1.79 


$0.28 


1967 


.64 


1968 


.57 


Mine B: 3 

1966 


.43 


1967 


1.08 


1968 


.89 


Mine C : 3 

1966 


.20 


1967 


.44 


1968 


1.47 


Average: 5 

1966 


.24 


1967 


.52 




1.26 



Capital expenditure written off over 10 years; some totals in RMC report (10) 

appeared to be wrong, so recalculated values were used. 
2 Cost of air courses amortized over 5 years. 
3 Data are for 1st half of year. 

4 1966 output of mine B was not available; assumed by extrapolation, 
individual mine data averaged by tonnage ore output. 



The owners of the five larger mines reported total capital assets in the 
original data, but Spencer used only the incremental capital expenditures for 
the period of interest. Therefore, certain capital costs did not contribute 
to the 1966-68 working level reductions. However, the improvements in concen- 
tration are shown as functions of new capital investments and increased oper- 
ating and maintenance costs. The working level averages given in their tables 
are not based on personal exposures but are simple arithmetic averages of per- 
iodic readings taken by the mine operator in the occupied areas of the mine. 
In one sense, since most of the underground workers are in areas of higher 
radon concentration, the average exposure might be higher than the data indi- 
cate. Further analysis (based on some additional information supplied by the 
owners) indicated that, for the period studied, average exposures and aver- 
age working levels were equal. A summary of the five-mine data is given in 
table 4. 



TABLE 4. - Radon-daughter control costs for five large uranium mines (10) 



Mine and year 


Mine average 
WL's 1 


Ore output, 1 
10 3 tons 


Total costs 
per ton 2 


Mine D: 

1966 


2.0 
.8 
.4 

2.2 

1.1 

.5 

1.6 

1.4 

.5 

2.3 

1.3 

.7 

1.5 

1.1 

.6 

2.03 

1.18 

.55 


132 

115 

79 

237 
278 
154 

119 

184 
104 

212 
276 
150 

84 

154 

78 

157 

201 
113 


$0.76 
.86 


1967 


1968 3 


.92 


Mine E: 

1966 


.57 


1967 


.57 


1968 3 


.71 


Mine F: 

1966 


.67 


1967 


.87 


1968 3 


.84 


Mine G: 

1966 


.55 


1967 * 


.66 


1968 3 


.88 


Mine H: 

1966 


.64 


1967 


.51 


1968 3 


.74 


Average: 4 

1966 


.62 


1967 


.67 




.81 



^Original WL data, given for each half of each year, were weighted by ore 

output for each 6-month period to arrive at these yearly averages. 
2 Includes new capital costs at 10-yr writeoff. 
3 First half of 1968 only. 
^Some values recalculated from published table (10, table 3). 



The mathematical analysis, cost versus working level, of the three-mine 
data yielded a linear equation, and that of the five-mine data an exponential 
equation. Their calculations indicate that to keep the highest exposure under 
0.3 WL, the mine average must be 0.15 WL. Extrapolating to this low level, 
they estimated a cost of approximately $1.05 per ton. Thompkins (11) took 
exception to this calculation and drew another curve through their data, indi- 
cating that it would be impossible to achieve less than a 0.5-WL average, 
regardless of how much money was spent on ventilation. 



ADL Study 

The study by Arthur D. Little, Inc. (ADL) for the Federal Radiation Coun- 
cil (1) is the most thorough evaluation of costs relative to radon-daughter 
control that is available. ADL personnel selected a sample of 26 underground 
uranium mines that would represent the underground uranium mining industry. 
In addition, they covered the more important producing regions, including 
large and small mines, old and new mines, and mines with high and low emana- 
tion rates. For early 1970, at the time of radon-daughter sampling, the 
26 mines represented 29 pet of the mines, 81 pet of the production, and 88 pet 
of the underground employees in the United States. 

The information supplied by each mine operator included working levels 
and costs. Some operators furnished data on percentages of underground miners 
receiving exposures in various working-level-month (WLM) 4 ranges. They also 
supplied detailed mine maps showing the location of ventilation holes, fans, 
secondary air bags, measured working levels, and airflow at various points in 
each mine. The measurements recorded were taken in March 1970. From all of 
the working-level data, ADL personnel were able to calculate three figures to 
characterize the situation at each mine: 

1. Mine working-place average working level, which is the average of all 
working level readings reported in working places and access ways on the mea- 
surement day. 

2. Maximum working level, which is the highest value reported in any 
working place on the evaluation date. 

3. The "last man" working-level-month, which is the highest 1969 expo- 
sure recorded for an individual. The costs for ventilation and radiation con- 
trol included fan power, maintenance, heating, and labor for ventilation and 
sampling, as well as capital costs for ventilation holes and other ventilation 
equipment . 

After gathering the baseline information, ADL had a team of mining, 
ventilation, and radiation control experts study each mine to establish the 
changes that would be necessary to assure that a reading of 0.3 or 0.6 WL 
would not be exceeded in any working or travel area. These would then equate 
4 or 8 "last man" WLM exposures. A design was developed for each mine to 
assure satisfying the 4 and 8 WLM per year standards. The incremental costs 
were calculated using standard unit costs. New investments such as additional 
drill holes, fans, bulkheads, and air heaters were included. The additional 
operating costs for power, labor, fuel, and supplies were also considered. 
Amortization for new capital items was done against 1 year's ore production 
from the mine. This procedure does result in higher costs than would be 
expected if the amortization was done more on a basis of the total ore 
reserves, if these had been known. Data extracted from the ADL report are 
given in table 5. 

^Inhalation of air containing a radon-daughter concentration of 1 WL for 
173 hr results in an exposure of 1 WLM. 



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ANALYSIS 

Since these studies spanned a 5-year period, the cost data should be put 

on a common base before analysis. The Consumer Price Index (CPI), also known 

as Cost of Living Index, was used to change all costs to 1967 dollars (1967$); 
hence CPI = 100 in 1967. 

The Federal Radiation Council data (6) first required a calculation of 
the estimated tonnage for the mines over a 10-year period. In 1965, the 
11 mines (table 1) produced over 20 pet of the total U.S. production, 5 which, 
at exactly 20 pet, amounts to 872,523 tons of ore. Therefore, the 10-year 
production is over 8.73 million tons. Table 6 gives the ventilation control 
costs converted to dollars per ton. The three small mines produced approxi- 
mately 87,252 tons of uranium ore in 1965, or approximately 0.52 million tons 
in the 6-year analysis period (table 6). The working level month figures and 
1967 dollars per ton are plotted in figure 1. 

TABLE 6. - Federal Radiation Council Report 8 (_6) uranium mine ventilation 

cost data converted to 1967 dollars per ton 



Item 


Total cost, 
millions 


Cost per ton 


Mine index 
or average WL 


WLM 




In 1965$ 


In 1967$ 




11-mine study (10-yr): 
Minimum ventilation. 

3-mine study (6-yr): 
Minimum ventilation. 
Control to 1.5 WL... 


$4.8 
11.8 
19.3 

.18 
1.01 


$0.55 
1.35 
2.21 

.34 
1.93 


$0.58 
1.43 
2.34 

.36 

2.04 


Ho 

2 

1 

^-20 
31.5 


120 
24 
12 

2 150 
18 



Estimate of average WL with normal metal mine ventilation practice. 
2 Midrange, 12.5 WL, used to calculate WLM. 
3 Average concentration. 

It is assumed that the costs supplied to Spencer (10) by the mine owners 
are CPI-corrected for each year during 1966-68. Table 7 summarizes the data 
and the conversions to 1967 dollars (1967$). These data and the production- 
weighted averages for all eight mines are also plotted in figure 1. As 
expected, because of the much greater tonnage, the weighted average is very 
close to the values for the five larger mines. Cross (5) pointed out that 
Spencer (10) neglected the succeeding years' equipment amortization and return 
on investment. This may have resulted in a cost understatement of 20 percent; 
the corrected data are also plotted in figure 1. 



5 Total U.S. production in 1965 was 4,362,614 tons (3). 



10 



TABLE 7. - Uranium mine ventilation cost data from Spencer (10) , 

converted 1967 dollars per ton 



Item 


Cost per ton 


Cost, 1967 dollars 
per ton 


Average 
WL 


WLM 


Three smaller mines: 

1966 


$0.24 

.52 

1.26 

.62 
.67 
.81 


$0.25 

.52 

1.21 

.64 
.67 
.78 


1.66 

1.50 

.55 

2.03 

1.18 

.55 


20 


1967 


18 


1968 


6.6 


Five larger mines: 

1966 


24 


1967 


14 




6.6 



10. 
9 
8. 

7. 
6 

5. 

4. 

c 

2 3. 

r>» 
<o 
o> 2. 



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o 
o 

z 
o 



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.8 
.7 

6 _ 



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+ 
8 



+ 



+ 

s 



J Ill 



KEY 
O 1 1-mine study. FRC 

V 3-mine study, FRC 

O 5 larger mines, RMC 

x 3 smaller mines, RMC 

Weighted average of RMC data 



D 

+ 



RMC weighted average 
corrected for 20% cost error 
by Cross (5) 



H Average cost and WLM data, ADL 

A Estimated weighted average of 
ADL data 



10. 100. 

AVERAGE ANNUAL EXPOSURE. WLM 

FIGURE 1. - Cost per ton for ventilating uranium mines. 



1,000. 



11 



The ADL study (1) had as its sole purpose to derive the total costs and 
impacts of decreasing the allowed radon-daughter exposure. The data for all 
26 mines are given in table 5. There is considerable scatter in the informa- 
tion; therefore, care was taken to arrive at reasonable averages. The authors 
of the ADL report provided production-weighted incremental costs to arrive at 
8 and 4 WLM exposures (table 5), but two key items are missing from the ADL 
survey — "present weighted average cost per ton" and "present average working 
level." These are estimated in two ways, arithmetic averages and using the 
observed differences in the average value and the ADL production-weighted 
average costs. These are given in table 8, and plotted in figure 1. 

TABLE 8. - Average ventilation costs and working place 
radon-daughter concentrations 





Cost per ton, 


Cost per ton, 








1970$ 


1967$ 


Average WL 




Item 


Using 


Using 


Using 


Using 


Average WLM 




table 5 


table 5 


table 5 


table 5 








averages 


weighted 
averages 


averages 


weighted 
averages 






Present conditions 


1.88 


1.03 


1.66 


0.91 


0.487 


5.8 


Last man = 8 WLM. . 


2.69 


1.53 


2.38 


1.35 


1 .451 


5.4 


Last man = 4 WLM.. 


5.19 


2.76 


4.59 


2.44 


!.226 


2.7 



*Ratio calculated from table 5 averages used to calculate average WL, 



The best values from the three studies are plotted together in figure 2, 
and a least-squares line, calculated in logarithmic space, has been drawn 
through the data. The equation for this line is 



1967$/ton = 3.134 (WLM)" - 3715 , 
with a correlation coefficient, R = -0.75. 



(1) 



The 95-percent confidence limit on the expected value of the mean is, in 
1967$/ton, approximately $1.10±$0.07, and for a particular value of the mean 
it is $1.10±$0.32. An equation was also calculated using the average val- 
ues. This equation has a steeper slope and larger intercept: 



and 



1967$/ton = 4.616 (WLM)" - h8 19 , 
R = -0.77. 



(2) 



In both cases, the fit is significant at the 0.01 level (99-percentile) , but 
the first equation is used in the remainder of this paper since it includes 
the corrections that are considered necessary. The exponential model 
developed by Cross (_5) from the individual mine data is given in cents per 
pound U3O8 (1969 dollars) versus average annual exposure. By converting their 
equation to dollars per ton (assuming 0.22 pet U3O3 ore grade) and 1967 
dollars, it becomes 



1967$/ton = 3.979 (12WL)" - 63 . 



(3) 



12 



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KEY 


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O 1 1-mine study. FRC 


— 












V 3-mine study , FRC 


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+ Weighted average of RMC 




**^^«^ A 




o 






data corrected for 20% error 
by Cross (5) 

A ADL data with corrected cost 
and WLM 






A 




V 


o 


,1967$/ton = 3.134 (WLM) ~° 3715 


— 




+ 


A 






/ R = -0.75 


— 






+ 




+ 




— 












^"""^^O 


— 












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1 1 


Mill 


II 


I 


1 


I I I I III I I I I I I II 



3 _ 



I. 



10. 100. 

AVERAGE ANNUAL EXPOSURE. WLM 

FIGURE 2. - Costs for ventilating uranium mines versus average annual exposure with regression line. 



1,000. 



This equation has a larger intercept and a much steeper slope than the 
equation developed from weighted average costs and working levels. Higher 
cost estimates for control to 1- to 2-WLM annual exposures results when this 
equation is used. 

APPLICATIONS 



Equation 1 can be used with some limitation to estimate the industry 
average cost for ventilating uranium mines at any desired average working 
level at any consumer price index and provide comparisons with other radiation 
control costs. 



13 



The inflationary rise in the Consumer Price Index since 1965 is shown in 
table 9. Since the data used in the analysis were converted to the 1967 base 
CPI, it is a simple matter to multiply the calculated cost per ton by the new 
CPI divided by 100, as follows: 



$/ton = 3.134 -y|| (WLM)-°' 3715 , 

= 0.03134 CPI(WLM)-°» 3715 . 
An example for CPI = 250 (1980$) is given in table 10 and figure 3. 
TABLE 9. - Consumer Price Index (based on 1967 = 100) 



1965.... 


94.5 


1972 


125.3 


1979 


217.6 


1966 


97.2 


1973.... 


133.1 


1980.... 


246.9 


1967 


100.0 


1974 


147.7 


1981: 




1968.... 


104.2 


1975 


161.2 


Jan. . . 


260.7 


1969 


109.8 


1976 


170.4 


Feb... 


263.5 


1970 


116.3 


1977 


181.5 


Mar. .. 


265.2 


1971.... 


121.3 


1978 


195.3 


Apr . . . 


266.8 



TABLE 10. - Cost per ton at CPI = 250 (1980$) 
for several average WLM exposures 



Average 


WLM 


Cost per ton 




At CPI = 100 


At CPI = 250 


4 




$1.87 


$4.68 


2 




2.42 


6.06 


1 




3.13 


7.84 


.7 




3.58 


8.95 



(4) 



14 



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10. 
9. 
8. 
7. 








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6. 
5. 
















4. 

3. 

2. 


0.7 WLM 
1 


" last 
WLM " 


man" 
last n 
2 WL 


I 

lan" 
M * \i 


ist 










4 WLM * last man 




1. 
.9 
.8 












.7 












.6 












.5 












.4 






* 






.3 












.2 
.1 




I I 


I I I I I 


II I 


i i 1 1 1 mi mi 



I. 10. 

AVERAGE ANNUAL EXPOSURE. WLM 



I00. 



FIGURE 3. 



Projected radiation control cost for different Consumer Price Indices and 
average annual exposure. 



At this point, the "last man" exposure should be introduced. If an 
average working level exposure of 4 WLM is maintained, some miners will be 
overexposed. Therefore, we should make the projections based on limiting the 
maximum exposure. Information in the ADL report (1) indicated a factor of 
1.478 between the average working-level-month exposure and the "last man" 
exposure. After incorporating both "last man" exposure and consumer price 
index, equation 1 becomes — 



DPT = 0.03624 CPI (LME) -0 ' 3715 , 

where DPT = dollars per ton corrected for CPI, 

and LME = limiting miner exposure (the highest annual 

exposure received by an underground employee). 



(5) 



15 



Table 11 gives an example of several limiting exposures at a CPI of 250. 
information, along with several other CPI's, is shown in figure 4. 

TABLE 11. - Cost per ton at CPI = 250 for several 
limiting miner exposures WLM 



This 



Limiting miner 


expo 


sure, 


Average 


WLM 


Cost per ton 


WLM 










at CPI = 250 


4 






2.71 




$5.41 


2 






1.35 




7.00 


1 






.68 




9.05 


.7 






.47 




10.34 



c 
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w 
o 
o 

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o 
a. 

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o 



30. 



20. 



10. 
9. 
8. 
7. 

6. 
5. 
4. 



1. 















— ^^^ 




o^\^ 


— 




^^^\\^ 


— 




^^T^\^\^^^ 


— 






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I I I I I Mil I II 



.1 



1. 10. 

LIMITING MINER EXPOSURE, WLM 



100. 



FIGURE 4. - Project radon-daughter control costs versus limiting miner exposure WLM 
for several Consumer Price Index values. 



16 



In looking at these projected costs for radiation control in uranium 
mines, it is apparent that they are significant. The underground uranium ore 
production in 1979 was approximately 6 million tons (8). Therefore, the esti- 
mated present cost is over $32 million per year if the industry is truly main- 
taining 4 WLM. If the limit is reduced to 2 WLM, the estimated total cost is 
$42 million; for a 1-WLM limit, it is $54 million, and for a 0.7-WLM limit, it 
is $62 million. Clearly, any change in permitted exposure levels can have a 
serious economic impact on mining costs. Also, as mines become deeper and 
larger than the mines in the 1965-70 base period, the total cost for ventila- 
tion is going to increase significantly, unless other control measures, are 
used to cut the ventilation requirements. 

COST OF OTHER CONTROL MEASURES 

Even with the present cost, we should be looking at all of the other 
available control measures. In recent years there has been an attempt by the 
Bureau of Mines and others to arrive at cost factors for other control tech- 
niques. The U.S. Environmental Protection Agency (EPA) sponsored a 2-month 
study that resulted in a report by Kown (9). This study considered the mine 
as a whole and its total production of radon, 8.86 Ci/day. Some of the radon 
reductions and costs given by Kown (9) are shown in table 12. Other control 
measures such as mine pressurization, the use of highly reactive chemical 
oxidants, and specialized mining techniques were discussed, but costs were 
not calculated. 

TABLE 12. - Costs for radon control from Kown (9) 



Control measure 


Radon reduction, 
Ci/day 


Cost per 
ton 


Activated charcoal 
with bulkheading.... 


1.01 
2.95 

3.01 


$1.45 
.34 

4.32 



Cost figures reported by the Bureau of Mines are usually for single 
installations. For example, the materials cost of an 8- by 14-foot bulkhead 
was $186 to $295 (_7)» Radon barrier sealant costs per square foot have been 
$0.30 to $1.19 ($0.46 to $1.84 in 1980 dollars) (4). The most expensive coat- 
ing system was the least satisfactory material because it contained chopped 
fiberglass. Field tests of sealants showed radon-stopping power of up to 
7 5 percent; therefore, they can reduce the amount of ventilation needed to 
control the radon-daughter concentrations to a given level. 

Cost figures like these can be compared with the cost for ventilation 
control. To accomplish this, the cost of a control measure must be expressed 
in the same units as ventilation costs — dollars per ton — and the effect of the 
new control measure must be defined. For example, cost per square foot is the 
most convenient for sealant coatings, and this can be related to a cost per 
ton by considering the surface area remaining in the excavation of typical 
drifts. In a 6- by 7-foot opening, about 8.2 square feet of rock is exposed 
around the periphery for each ton of rock removed; for a 12- by 14-foot 



17 



drift, about 4.1 square feet of surface is left per ton of rock removed. 
Therefore, sealant coatings cost about $2 or $3 per ton (1980). This is con- 
siderably less than the estimated $5.43 per ton for present radon-daughter 
control. 

CONCLUSIONS 

The available radiation control cost information has been analyzed and 
yielded the equation: Cost, 1967$/ton = 3.134 (WLM)~ ' 3715 . Combining limit- 
ing miner exposure, LME, and consumer price index, CPI, the dollars per ton 
(DPT) can be estimated from DPT = 0.03624 CPI (LME)" * 3715 . The 1967 cost per 
ton for a number of average and limiting miner working-level-month exposures 
has been calculated and converted to a 1980 CPI value. At a LME of 4 WLM, the 
projected cost per ton for radiation control is $5.41. If the LME is reduced 
to 0.7 WLM, the projected cost per ton is $10.34. These values are only 
applicable to radiation control in U.S. sandstone-type mines. Considering 
the projected costs per ton, any reasonable technology should be used in the 
control of radon and radon-daughters. 



ma 



18 



REFERENCES 

1. Arthur D. Little, Inc. An Assessment of the Ecomonic Effects of 

Radiation Exposure Standards for Uranium Miners. Rept. to the Fed. 
Radiation Council, November 1970, 2d ed. , 250 pp. 

2. . Advanced Techniques for Radon Gas Removal. BuMines Open File 

Rept. 60-75, May 1975, 209 pp. ; available for reference at BuMines 
facilities in Pittsburgh, Pa., Denver, Colo., Spokane, Wash., and Twin 
Cities, Minn.; at the National Library for Natural Resources, 

U.S. Dept. of the Interior, Washington, D.C.; and at the Dept. of 
Energy facility in Morgantown, W. Va. ; available from National Tech- 
nical Information Service, Springfield, Va. , PB 243 898; BuMines 
contract H0230022. 

3. Baroch, C. T. Uranium. Ch. in BuMines Minerals Yearbook 1965. V. 1. 

Metals and Minerals (Except Fuels), pp. 973-991. 

4. Bates, R.C., and J. C. Franklin. U.S. Bureau of Mines Radiation 

Control Research. Proc. Conf. on Uranium Min. Technol. , Reno, Nev. , 
Apr. 25-29, 1977, 32" pp. 

5. Cross, F. T. , C. H. Bloomster, P. L. Hendrickson, and I. C. Nelson. 

Evaluation of Methods for Setting Occupational Health Standards for 
Uranium Mines. Nat. Inst, for Occupational Safety and Health, NIOSH 
Rept. 72-2, 1974, 237 pp.; available from Nat. Tech. Inf. Service, 
Springfield, Va. , PB 237 744; NIOSH contract HSM-99-72-135, 
Battelle-Pacif ic Northwest Laboratories. 

6. Federal Radiation Council. Guidance for the Control of Radiation Hazards 

in Uranium Mining. FRC Rept. 8, rev. September 1967, 60 pp. 

7. Franklin, J. C. , C. S. Musulin, and D. W. Thebeau. Research on Bulkheads 

for Radon Control in Mines. Proc. Update on Uranium Min. Technol. , 
Reno, Nev., Nov. 13-17, 1978, 11 pp. 

8. Klemenic, J. Production Capability. Proc. Update on Uranium Min. 

Technol., Reno, Nev., Nov. 13-17, 1978, 30 pp. 

9. Kown, B. T. , V. C. Van der Mast, and K. L. Ludwig. Technical Assessment 

of Radon 222, Control Technology for Underground Uranium Mines. 
Bechtel National, Inc., San Francisco, Calif. Task 9, 1979, 61 pp. 

10. Spencer, N. , L. Spittel, T. Towles, and G. Lady. Control of Radiation 

Exposure in Uranium Mines: A Cost and Economic Analysis. Resource 
Management Corp., Rept. UR-42, prepared for the Federal Radiation 
Council, November 1968, 66 pp. 

11. Thompkins, R. W. Radiation Control in North American Mines and Their 

Effects on Mining Costs. Proc. 7th Internat. Min. Cong., Bucharest, 
Romania, September 1972, pp. 1-11. 

« U S. GOVERNMENT PRINTING OFFICE : 1981 358-313/7175 



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